MEP-804A Low frequency issue

[Jbuck]

I have a 804A that has run great for several years now I can’t get the HZ to come above 48. I have replaced the MPU with no change. Then I replaced the Eletronic Governor control with no luck ( not sure I have it adjusted correctly). I am at a loss. Voltage is good but HZ is not. Frequency adjustment changes RPM but does not bring it up high enough. Any suggestions would be greatly appreciated.

 

[Scoobyshep]

I have a 804A that has run great for several years now I can’t get the HZ to come above 48. I have replaced the MPU with no change. Then I replaced the Eletronic Governor control with no luck ( not sure I have it adjusted correctly). I am at a loss. Voltage is good but HZ is not. Frequency adjustment changes RPM but does not bring it up high enough. Any suggestions would be greatly appreciated.

Are you using the sets frequency meter or a handheld? I suggest using a known good multi meter to verify first.

Sent from my SM-S908U using Tapatalk

 

[Jbuck]

I have verified it with a fluke meter and it says 49 HZ. I did replace the governor control but had no idea where to adjust it to

 

[Icesythe7]

I have verified it with a fluke meter and it says 49 HZ. I did replace the governor control but had no idea where to adjust it to

Did you try adjusting as per the TM yet?

 

[peapvp]

Verify that you have indeed 24V on Terminal 1

 

[Jbuck]

I have the eletronic govenor control. I seen a post here on adjustment but can’t find it. I remember they said it was a PITA to change it

 

[Guyfang]

Try looking at this. Unless you can SEE that someone has fooled with the linkage, do not fool with it. The only time it needs adjusting, is when someone did not read the book and fooled with it. Or replaced it, and did not read the book.

 

[Guyfang]

Also, Jbuck,

You need to write the state you live in, in the location block, IAW the forum rules.

 

[justinn]

I have verified it with a fluke meter and it says 49 HZ. I did replace the governor control but had no idea where to adjust it to

I have an 804B that had a similar problem, well, 2 problems actually. I need to get back out there to give you the correct terminology for what I adjusted as I am most familiar with the 003A's and the 802/803A's. It may have been the governor control(it was the doohickey on the upper right of the panel behind the gauge panel-FREQ rheostat IIRC). It needed about a 3-4 degree turn to get it spot on with the Fluke. There was a paint mark on it and it was still within the paint mark after moving it, so it wasn't a big move at all.

Now on to the 2nd problem.... the factory gauge was sticking, so the next time I started it up, it was showing under 50 HZ, I was like WTF! Couple of taps to it with the ol' index finger and she was reading good again. I have zero faith in that gauge

I'll try to get out to the property this week and I'll take a picture of exactly what I adjusted. I need to find a questionable connection to the main fuel pump anyway. Unfortunately, I "borrowed" a wheel off of the trailer for another HMMWV, so I need to get creative to get it back in to the barn to work on it(107 degree temperatures and me ain't so fond of one another).

Justin

I REMEMBER NOW!!! The rheostat was maxed out and it was still low. That's why I fiddled with the governor control(FREQ) so I could get a little more adjustment out of it! Credit goes to the post a couple posts down that showed the picture I was looking for.

And one more kind of funny thing..... apparently someone in the poor gen's previous life thought that by turning the rheostat on the panel PAST its stop, they could get a couple more Hz out of it so the rheostat on the back was pushed out of the housing(they turned it so hard that it bent the tabs holding it together). I had to laugh at that one as quite a few times in life, I have wanted todo the same thing.

 

[justinn]

Has it been run regularly? Have fresh fuel in there? If it's struggling on one of the cylinders, that could be affecting it as well.

 

[Jbuck]

I have an 804B that had a similar problem, well, 2 problems actually. I need to get back out there to give you the correct terminology for what I adjusted as I am most familiar with the 003A's and the 802/803A's. It may have been the governor control(it was the doohickey on the upper right of the panel behind the gauge panel-FREQ rheostat IIRC). It needed about a 3-4 degree turn to get it spot on with the Fluke. There was a paint mark on it and it was still within the paint mark after moving it, so it wasn't a big move at all.

Now on to the 2nd problem.... the factory gauge was sticking, so the next time I started it up, it was showing under 50 HZ, I was like WTF! Couple of taps to it with the ol' index finger and she was reading good again. I have zero faith in that gauge

I'll try to get out to the property this week and I'll take a picture of exactly what I adjusted. I need to find a questionable connection to the main fuel pump anyway. Unfortunately, I "borrowed" a wheel off of the trailer for another HMMWV, so I need to get creative to get it back in to the barn to work on it(107 degree temperatures and me ain't so fond of one another).

Justin

I REMEMBER NOW!!! The rheostat was maxed out and it was still low. That's why I fiddled with the governor control(FREQ) so I could get a little more adjustment out of it! Credit goes to the post a couple posts down that showed the picture I was looking for.

And one more kind of funny thing..... apparently someone in the poor gen's previous life thought that by turning the rheostat on the panel PAST its stop, they could get a couple more Hz out of it so the rheostat on the back was pushed out of the housing(they turned it so hard that it bent the tabs holding it together). I had to laugh at that one as quite a few times in life, I have wanted todo the same thing.

I have not quite convinced myself that it is govenor control yet. One time I start it it will run perfect. The next time it will run like someone is chocking the air off to it. So I think it might be the fuel transfer pump not supplying enough fuel. I have replaced the govenor ( ouch ). Replaced the MPU and it is at 2.8 volts. I can adjust the speed with the frequency control. Sometimes it will be running at 50 hz then just jump to full throttle because I have the frequency control maxed out. Turn it down and it runs fine until next time. I am convinced it has nothing to do with the generator just motor control.

 

[justinn]

I have not quite convinced myself that it is govenor control yet. One time I start it it will run perfect. The next time it will run like someone is chocking the air off to it. So I think it might be the fuel transfer pump not supplying enough fuel. I have replaced the govenor ( ouch ). Replaced the MPU and it is at 2.8 volts. I can adjust the speed with the frequency control. Sometimes it will be running at 50 hz then just jump to full throttle because I have the frequency control maxed out. Turn it down and it runs fine until next time. I am convinced it has nothing to do with the generator just motor control.

Once it's running well, does it remain running well until you shut it down(even hours later)? I didn't realize that it was intermittent. So I don't think it's actually related to the governor or anything electrical now.

Do you have an infrared thermometer? When it's experiencing the issue, can you temp check each cylinder coming off the head?
This may help to narrow it down to a single cylinder. If the variation in RPM is that big, it almost sounds like you have a cylinder down and when it clears up, you get the full Monty and the rpm shoots up. Could be fuel related, but I suggest trying to narrow it down to a single cylinder. Once you've determined if it's a single cylinder exhibiting the symptoms, we can help to narrow it down for you. If it's not fueling, it could be a sticky valve.

Justin

 

[Tinstar]

Jbuck
Second Warning about location